Dual purpose gaseous discharge tube



Nov. 20, 1934.

A. HUND DUAL PURPOSE GASEOUS DISCHARGE TUBE Filed July 29, 1932 2 Sheets-Sheet 1 24/ SOURCE INVENTOR August Hurui I ATTORNEY Nov. 20, 1934. A. HUND DUAL PURPOSE GASEOUS DISCHARGE TUBE Filed July 29, 1932 2 Sheets-Sheet 2' m an a m M E O V 11 W ME A nu INPUT Patented Nov. 20, 1934 UNITED STATES 1,981,359 DUAL PURPOSE GASEOUS DISCHARGE TUBE August Hund, West Orange, N. J., assignor to Wired Radio, Inc., New York, N. Y., a corporation of Delaware Application July 29, 1932, Serial No. 625,621

4 Claims.

This invention relates to gaseous discharge tubes and more particularly to a tube of this type characterized by having duplicate sets of electrodes within a single envelope whereby the tube may be caused to function either as a detector and successive amplifier, as a two-stage amplifier, or as a push-pull tube.

An object of my invention is to provide such a tube having a structure which enables it to function efficiently for any of the purposes aforementioned.

Another object of my invention is to so arrange the elements of a dual purpose gaseous discharge tube that one such tube may be used to advantage in place of two tubes of other well known types.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, together with its objects and advantages may best be understood by reference to the following description taken in connection with the accompanying drawings in which:

Figure 1 is a view of one form of my dual purpose tube showing diagrammatically a two-stage radio receiving circuit for which it is adapted.

Figure 2 shows a modified form of my dual purpose tube connected into a typical push-pull circuit to illustrate one of a variety of applications to which the tube is adapted.

Referring to Figure l, I show a gaseous discharge tube 1 which comprises an envelope 2, base 3, the usual prongs 4., and preferably a plurality of connector tips 5, 6; and within the envelope an electrode structure having insulated 5 connections to the several prongs and connector tips whereby the electrodes may be activated.

The electrodes may be formed in a variety of ways, some of which are illustrated in my copending application Serial No. 624,920, filed July 27, 1932. For example, the ionizing cathode 7 may be in the form of a simple wire ring opposed to which is an ionizing anode 8 in the form of a crimped ring. In the tubes of my present invention these electrodes are duplicated at 9 and 10, respectively. The two ionizing cathodes 7 and 9 are preferably supported by a post of insulating material within which is a conductor common to both cathodes and connected with one of the prongs 4. A similar post of insulating material is shown containing a conductor from one of the prongs 4 to the two ionizing anodes 8 and 10. Surrounding the axially disposed work anode 11 is a control electrode 12 which may be in the form of a simple wire'helix supported by a post of insulating material which contains a conductor leading to the connector tip 5. y

From the foregoing description it will be seen that the ionizing electrodes 7 and 8 and the work electrodes 11 and 12 of themselves form a comno plete system such as shown in my aforementioned copending application. Asecond complete system is shown within the envelope of the tube and comprises the ionizing electrodes 9 and '10. the work anode l3 and the control electrode 14. 05 When, therefore, the electrodes of the two systems are suitably connected into a receiving circuit, for example, having either a detector and an amplifier, or having two stages of amplifica tion, the one tube serves all the'purposes of two 7 ordinary thermionic tubes.

In order to illustrate one application of my dual purpose gaseous discharge tube, I have shown in Figure 1, a radio receiving circuit in which is provided an antenna 15, an antenna coil 16, a tunable input circuit having an impedance 17 coupled with the antenna coil 16, and a variable condenser 18. This inputcircuit is connected on one side to the control electrode 12 and on the other side to a tap'19 oif of a voltage so divider 20 by which the potential supplied to the control electrode 12 may be suitably biased with respect to the potential'of the ionizing anode 8;

The voltage divider 20 is placed across the terminals of a source of direct current 21 and vari- 35 one taps leading therefrom serve to impress upon the several electrodes of the tube such potentials as may be required in'each case. ThusQthe tap 22 connects with the two ionizing anodes 8 and 10; the tap 23 provides a higher potential to be impressed upon the work anode 11 through the primary coil of the transformer 25, while a still higher potential may be derived from the positive pole of the battery itself to be impressed upon the work anode 13 through the circuit, which includes the primary coil of an output transformer 24. l

The primary winding of transformer 25 is in the output circuit of the detector stage. The secondary of this transformer is in the input cir- 10o cuit of the second stage. It connects on one side to control electrode 14 and on the other side to tap 26 on the voltage divider which serves to impress upon this control electrode a suitable bias with respect to the ionizing anode 10.

Bypass-condensers- 27 maybe employed in the usual manner wherever it is desirable to shunt high frequency or other alternating currents around resistances such as the battery 21 or the voltage divider20.

In the operation of the tube of my invention as illustrated in Figure 1, it will be seen that radio freuqency signals received upon the antenna 15 are impressed upon the control electrode 12. Due to the ionization which takes place in the region of the electrodes 7 and 8, and due further to a characteristic of this tube which enables me to setup secondary ionization in the neighborhood of the work anode 11, the space current set up by the ionizing electrodes and flowing towards the work anode 11, is very efiiciently controlled for the purpose of demodulating the incoming signals. The demodulated signals'are therefore impressed upon the primary coil of the transformer 25. Between the primaryand-the secondary of this transformer any suitable stepup ratio may be providedwhereby the output current may be taken off the terminals of the secondary coil at a higher voltage and impressed upon the input circuit which includes the control electrode 14 and the ionizing anode 10.

A stage of amplification is then provided by the electrodes in, the lower portion of the tube. Electrodes 9, 10, 13 and'14 function as an amplifier by virtue of the primary ionization existing between the electrodes 9 and 10, as well as by secondary ionization in the region of the work anode 13, which is in the output circuit including the primary coil of the transformer 24.

' It will be noted that part of the potentiometer 20 'acts as a protective resistance to prevent excessive currents flowing across theregion of primary ionization.

In'carrying out my invention according to actual'tests that have been made upon the dual purpose tubes constructed as shown, substantially thesame characteristics for detection and amplification are exhibited as in the case of the single purpose tubes of my aforementioned copending application, Serial No. 624,920, filed July 27, 1932. The principles of operation are substantially the same, but with the dual purpose tube there is the advantage thatthe tube may be used in two stages and with a resulting economy of space',and there are only two terminals for the four ionizing electrodes;

Referring now'to Figure 2, I show an entirely different application of a dual purpose tube. A modification of the tube construction is also shown wherein the ionizing electrodes 28 and 29 are disposed along the axesof the two systems, while the respective work anodes 30 are preferably in the form of aring made of flat'metal surrounding the ionizing cathode 28. This particular construction has the advantage that it provides a high input impedance.

The control electrodes13 and 14 intervene between the ionizing electrodes and the work anode of each system. The remaining details of the tube construction, according to Figure 2, will be seen to be similar to those of the embodiment shown in Figure 1. "i

From Figure 2 it will be seen that the tubes of my invention are well adapted to a push-pull network. For example, the diagram shows an. input transformer 31, the primary coil of which may be connected with any source of incoming signals. The secondary coil of this transformer forms one branch of a tuned circuit, the other branch of which comprises the tuning condenser 18. For cases where tuning is not desirable, the condenser 18 may be omitted. A proper bias potential isimpressed upon the mid-point of the secondary coil 32, the potentialitself being determined by the position ofthe adjustable tap 33 on the potentiometer 34. The two terminals of the potentiometer are connected across the source of direct current 21. The two sides of the tuned input circuit are connected, respectively, with the control electrodes 13 and 14, the electrode 13 being supported by a post which leads to the connector tip 5, and the electrode 14 being supported by a post which contains a conductor leading to one of the prongs 4 inthe base of the tube.

Not only the input circuit, but also the output circuit of this tube may be arranged to operate in a push-pull manner. As illustrated, the output circuit comprises the work anodes 30, one of which is supported by a post leading to the connector tip 6, and the other of which is supported by a post containing a conductor which leads to one of the prongs 4, in the base of the tube. This output circuit includes the primary coil 35 of an output transformer 3'7, which coil is provided with a center tap connected at the contact 36 with the potentiometer 34, whereby a suitably high potential above that of the ionizing anodes 29 may be obtained. The output transformer 3'7 may be of the air-core type when high frequency signals are to be amplified, or it may have an iron core as when audio signals are to be amplified. The alternative use is thus-inindicated by broken linesrepresenting the trans former core.

Direct current for the ionizing electrodes-28 and 29 is derived from the source 21, the positive side of which leads through the potentiometer-34 to the adjustable tap 38, and thence to that prong 4 which, connects with the insulated conductor 39 leading to and supporting the ionizinganodes 29. The negative side of the direct current source is directly connected through one of the prongs 4 with an insulated conductor 40 leading to and supporting the ionizing cathodes 28. Bypass condensers 27 are preferably introduced across suchpoints as would offer an unnecessarily high impedance to alternating currents of the work circuits, all of these bypass condensers being preferably'connected on one side to the conductor 41, which connects with the ionizing anodes.

Bearing in mind that the tubes of this invention are characterized in their operation by having a primary glow set up in the region ofthe ionizing electrodes, and that'a suitable potential is impressed upon the work anodes, whereby a secondary glow is formed in the region thereof, it will be readily understood that the tube as shown in Figure 2 isadmirably suited to the purposes of a push-pull network. Theoperation of the tube will therefore be readily understood from the foregoing description. It will be further uriderstood that'either of the two types of tubes shown may be employed in a push-pull network andeither may be used in a two-stage network. Other types of tubes having modified arrangements of the electrodes may also be found to have advantageous features, and still be comprehended within the scope of my invention.

It will be understood that the circuit of Figure 2 can beused for push-pull demodulation as well as for push-pull amplification. For this purpose it is only necessary to adjust the control bias to a suitable value. 11y seen that it is within thescope of theinvention to use the dual purpose tube as a'two-stage amplifier, the connections being similar to the circuit diagram of Figure 1; the upper tubestructure, comprising electrodes 7, 8,11 and 12, being P Then, again, it isread-"f in one stage and the lower structure, including electrodes 9, 10, 13 and 14 being in a second stage.

In carrying out my invention by the use of a dual purpose tube, a very practical advantage is obtained over the use of two ordinary radio tubes, particularly in cases where it is essential for the characteristics of one tube to be matched by those of another. In a dual purpose tube the two electrode systems are bound to operate under identical conditions of attenuated atmosphere, and of potential difierence applied across the ionizing electrodes. Thus the matching problem is substantially eliminated.

Various modifications of my invention other than as herein shown and described may suggest themselves to those skilled in the art. No limitations, therefore, are intended to be imposed, other than as indicated by the scope of the claims.

I claim:

1. A dual purpose gaseous discharge tube comprising, a sealed envelope containing an attenuated gas and a plurality of electrodes arranged in two similar electrode systems, each of said systems including a pair of ionizing electrodes across which a suitable potential drop may be established for setting up a primary ionization discharge therebetween, each of said electrode systems having an output anode and a control electrode and means including said primary ionization electrodes for establishing a secondary ionization discharge co-axial with said primary ionization discharge and in the vicinity of each of said output anodes.

2. A dual purpose gaseous discharge tube comprising, an envelope containing an attenuated gas, a plurality of cathodes and cooperating anodes therefor within said envelope, a work anode associated with each of said cathodes and anodes, an open mesh control electrode associated with each of said work anodes, means for simultaneously energizing said cathodes and anodes to produce therebetween primary ionization dis-- charges and means cooperating with each pairof said primary ionization electrodes for producing a secondary ionization discharge in the vicinity of each of said work anodes and substantially coaxial respectively with said primary ionizations.

3. A dual purpose ionization discharge tube comprising, a sealed envelope containing an attenuated gas and a plurality of electrode systems, each of said electrode systems including a pair of ionizing electrodes across which a suitable potential drop may be established for setting up a primary ionization discharge therebetween, each of said systems having an open mesh control electrode substantially surrounding said ionizing electrodes, an output anode substantially surrounding said control electrode and means including said primary ionization electrodes for setting up a secondary ionization discharge coaxial therewith and in the vicinity of each of said output anodes.

4. A dual purpose gaseous discharge tube comprising, a sealed envelope containing an attenuated gas and a pair of electrode systems, each of said electrode systems comprising a pair of ionizing electrodes across which a suitable potential drop may be established for setting up a primary ionization discharge therebetween, each system having an output anode co-axially located with respect to said ionizing electrodes and an open mesh control electrode co-axial with said output anode and means including said primary ionization electrodes for causing a secondary ionization discharge substantially co-axial with said primary ionization discharge and in the vicinity of each of said output anodes. V

AUGUST HUND. 

